CN114951946B - A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel by using high-entropy alloy - Google Patents

Abstract

The invention provides a method for connecting tungsten-cobalt-based hard alloys and 42CrMo steels using high-entropy alloys, which is characterized in that (CoCrFeNi) _{1-x Cux} high-entropy alloys are used as transition layer materials, and the tungsten-cobalt-based hard alloys are treated by SPS technology. Carbide and 42CrMo steel are solid-phase diffusion welded to complete the connection between tungsten-cobalt cemented carbide and 42CrMo steel; where x=0.1‑0.5. The method provided by the present invention to connect tungsten-cobalt hard alloys and 42CrMo steels using high-entropy alloys uses (CoCrFeNi) _1-x Cu _x high-entropy alloys as transition layer materials, aiming at suppressing the generation of brittle phases at welds, reducing The residual stress improves the performance of the welding head, which in turn improves the overall reliability of cemented carbide and steel welding.

Description

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel by using high-entropy alloy

technical field

The invention relates to the field of welding technology, in particular to a method for connecting tungsten-cobalt hard alloy and 42CrMo steel by using a high-entropy alloy.

Background technique

Cemented carbide has a wide range of uses and can be divided into three categories: metal cutting tools, rock drilling tools and wear parts, while metal cutting is the largest market for tungsten-cobalt cemented carbide, but the manufacturing and processing of cemented carbide is difficult, and the formation of High cost, poor toughness and high brittleness, these factors greatly restrict the application of cemented carbide. At present, cemented carbide is connected to high-strength and high-toughness steel that is easy to process and manufacture, has excellent mechanical properties, and is cheaper than cemented carbide to form a tool with excellent comprehensive performance.

Diffusion composite technology is one of the connection methods between cemented carbide and steel. Diffusion welding is a kind of solid phase connection technology, which has many characteristics: because the substrate is not overheated and does not melt during welding, metal or non-metal can be welded without reducing the performance of the weldment; the joint quality is good, the precision is high, and the deformation Small; it can weld workpieces with complex structures, inaccessible joints and large differences in thickness; it can weld many joints in the assembly at the same time. At present, copper is mostly used as the "transition layer material" for diffusion welding of tungsten-cobalt cemented carbide and 42CrMo steel, and the price of copper is relatively high.

The physical properties such as linear expansion coefficient, melting point and specific heat capacity of cemented carbide and steel are quite different. Among them, the linear expansion coefficient of cemented carbide is much smaller than that of steel, which will cause cemented carbide and steel to be in different stress states during welding, which will lead to higher residual stress in the welded joint, which may cause the joint to crack. When the welding temperature is too high, the properties of the base metal will change, and if the welding temperature is low, defects such as pores will appear. At the same time, brittle phases are prone to appear during the welding process, and the joints are prone to embrittlement. Therefore, how to achieve low-cost and reliable diffusion bonding of tungsten-cobalt cemented carbide and 42CrMo steel has become a key problem in the application field of tungsten-cobalt cemented carbide.

In view of this, it is necessary to provide a new process to solve the technical problems of welding tungsten-cobalt cemented carbide and 42CrMo steel.

Contents of the invention

The technical problem to be solved in the present invention is to provide a method for connecting tungsten-cobalt hard alloys and 42CrMo steels using high-entropy alloys, using (CoCrFeNi) _1-x Cu _x high-entropy alloys as transition layer materials, aiming at suppressing the The generation of brittle phase reduces the residual stress, improves the performance of the welding joint, and improves the overall reliability of cemented carbide and steel welding.

In order to solve the above problems, the technical scheme of the present invention is as follows:

A method for connecting tungsten-cobalt hard alloys and 42CrMo steels using high-entropy alloys, using (CoCrFeNi) _1-x Cu _x high-entropy alloys as transition layer materials, and tungsten-cobalt hard alloys and 42CrMo steels by SPS technology Solid phase diffusion welding to complete the connection between tungsten-cobalt cemented carbide and 42CrMo steel; where x=0.1-0.5.

Furthermore, the (CoCrFeNi) _1-x Cu _x high-entropy alloy material is obtained by vacuum arc melting after the alloying elements are proportioned according to the atomic ratio.

Further, the method for connecting tungsten-cobalt cemented carbide and 42CrMo steel using high-entropy alloy specifically includes the following steps:

Step S1, base metal preparation: cutting tungsten-cobalt cemented carbide and 42CrMo steel into shapes to be welded, and performing pretreatment;

Step S2, assembly: Assemble the tungsten-cobalt hard alloy, 42CrMo steel and (CoCrFeNi) _1-x Cu _x high-entropy alloy material into the graphite mold, and the (CoCrFeNi) _1-x Cu _x high-entropy alloy material is located in the tungsten-cobalt Between cemented carbide and 42CrMo steel;

Step S3, discharge plasma SPS diffusion welding connection: put the graphite mold with the parts to be welded into the discharge plasma sintering system, heat up to the diffusion welding temperature under vacuum conditions, and then keep it warm for SPS diffusion welding.

Further, in step S2, the thickness of the (CoCrFeNi) _1-x Cu _x high-entropy alloy material is 100-2000 μm.

Further, in step S3, the diffusion temperature is 650-1000°C, the heating rate is 10-150°C/min, the holding time at the diffusion welding temperature is 5-30min, the diffusion pressure is 5-40Mpa, and the vacuum degree is ≤1×10 ^{− 3} MPa.

Compared with the prior art, the method provided by the present invention for connecting tungsten-cobalt hard alloy and 42CrMo steel with high-entropy alloy has beneficial effects as follows:

One, the method provided by the present invention adopts high-entropy alloy to connect tungsten-cobalt cemented carbide and 42CrMo steel, with (CoCrFeNi) _1-x Cu _x high-entropy alloy (wherein x=0.1-0.5, Cu(at%)=10 %-50%, the four elements of Co, Cr, Fe and Ni have equimolar amounts) as the "transition layer material" connecting tungsten-cobalt cemented carbide and 42CrMo steel, using spark plasma sintering technology (SparkPlasma Sintering, SPS) connection Tungsten-cobalt cemented carbide and 42CrMo steel, the (CoCrFeNi) _1-x Cu _x high-entropy alloy "transition layer material" used in the present invention is a dual-phase high-entropy alloy, one phase is a copper-rich phase, and the other phase is a poor Copper phase, according to the law of diffusion, at the interface formed by the tungsten-cobalt cemented carbide and the high-entropy alloy "transition layer material", the Co, Cr, Fe, Ni and Cu atoms of the high-entropy alloy "transition layer material" rapidly move to the tungsten Cobalt-based cemented carbide diffuses, and at the same time, the elements in the tungsten-cobalt-based cemented carbide with a higher concentration than the "transition layer material" diffuse to the "transition layer material" side, and the interface formed by the high-entropy alloy "transition layer material" and 42CrMo is also The high element concentration diffuses to the low concentration direction, but the brittle phase of the intermetallic compound is suppressed due to the existence of the high-entropy alloy. Finally, the high-entropy alloy "transition layer material" is combined with the tungsten-cobalt cemented carbide base material and the 42CrMo steel base material respectively. Form a welding interface layer with a small atomic concentration gradient and a certain thickness, and realize a smooth transition of the thermal expansion coefficient between the base metals through the "transition layer material", which is beneficial to solve the problem of excessive local residual stress caused by the mismatch of thermal expansion coefficients, resulting in welding The problem of crack initiation and rapid expansion at the interface. Through the method of the present invention, a higher-strength joint is obtained, and the tensile strength of the joint obtained by diffusion welding is greater than that of the joint obtained after simple copper welding, which provides a new method for connecting tungsten-cobalt hard alloy and steel method.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

Figure 1 shows the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy obtained by using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 1 and holding it at 900°C for 15 minutes Microstructure photo of "transition layer material"/42CrMo steel joint;

Figure 2 shows the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy obtained by SPS diffusion welding in Example 1 using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" and holding it at 900°C for 15 minutes Microstructure photo of the joint of "transition layer material";

Figure 3 shows the (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" obtained in Example 1 by using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of /42CrMo steel joint;

Figure 4 shows the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy obtained by using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 1 and holding it at 900°C for 15 minutes Interface EDS line scan results of the "transition layer material"joint;

Figure 5 shows the (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" obtained in Example 1 by using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes /42CrMo steel joint interface EDS line scan results;

Figure 6 shows the YG10X cemented carbide/(CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy obtained by using (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 2 and holding it at 900°C for 15 minutes Microstructure photo of "transition layer material"/42CrMo steel joint;

Figure 7 shows the YG10X cemented carbide/(CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy obtained in Example 2 by using (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of the joint of "transition layer material";

Figure 8 shows the (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material" obtained in Example 2 by using (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of /42CrMo steel joint;

Figure 9 shows the YG10X cemented carbide/(CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy obtained in Example 3 by using (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of "transition layer material"/42CrMo steel joint;

Figure 10 shows the YG10X cemented carbide/(CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy obtained by SPS diffusion welding in Example 3 using (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as the "transition layer material" and holding it at 900°C for 15 minutes Microstructure photo of the joint of "transition layer material";

Figure 11 shows the (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy "transition layer material" obtained in Example 3 by using (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of /42CrMo steel joint;

Figure 12 shows the YG10X cemented carbide/(CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy obtained by using (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 4 and holding it at 900°C for 15 minutes Microstructure photo of "transition layer material"/42CrMo steel joint;

Figure 13 shows the YG10X cemented carbide/(CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy obtained by SPS diffusion welding in Example 4 using (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as the "transition layer material" and holding it at 900°C for 15 minutes Microstructure photo of the joint of "transition layer material";

Figure 14 shows the (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material" obtained in Example 4 by using (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of /42CrMo steel joint;

Figure 15 shows the YG10X cemented carbide/(CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy obtained by SPS diffusion welding in Example 5 using (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as the "transition layer material" and holding it at 900°C for 15 minutes Microstructure photo of "transition layer material"/42CrMo steel joint;

Figure 16 shows the YG10X cemented carbide/(CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy obtained by using (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 5 and holding it at 900°C for 15 minutes Microstructure photo of the joint of "transition layer material";

Figure 17 shows the (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy "transition layer material" obtained in Example 5 by using (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes Microstructure photo of /42CrMo steel joint;

Figure 18 is a photo of the structure and morphology of the YG10X cemented carbide/pure copper "transition layer material"/42CrMo steel joint obtained by using pure copper as the "transition layer material" for SPS diffusion welding in Comparative Example 1 and holding it at 900°C for 15 minutes ;

Figure 19 is a photo of the microstructure of the YG10X cemented carbide/pure copper "transition layer material" joint obtained by using pure copper as the "transition layer material" for SPS diffusion welding in Comparative Example 1 and holding it at 900°C for 15 minutes;

Figure 20 is a photo of the microstructure of the pure copper "transition layer material"/42CrMo steel joint obtained in Comparative Example 1 by using pure copper as the "transition layer material" for SPS diffusion welding and holding at 900°C for 15 minutes.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned purpose, features and advantages of the present invention more obvious and understandable, the specific implementation manners of the present invention will be further described below.

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

A method for connecting tungsten-cobalt hard alloys and 42CrMo steels using high-entropy alloys, using (CoCrFeNi) _1-x Cu _x high-entropy alloys as transition layer materials, and tungsten-cobalt hard alloys and 42CrMo steels by SPS technology Solid phase diffusion welding to complete the connection between tungsten-cobalt cemented carbide and 42CrMo steel; where x=0.1-0.5.

Specifically, the following steps are included:

(1) Preparation of high-entropy alloy "transition layer material": (CoCrFeNi) _1-x Cu _x high-entropy alloy Weigh Co, Cr, Fe, Ni and Cu raw materials by molar ratio, and then rank them according to melting point from low to high Sequentially put into the crucible of the vacuum melting furnace, under the protection of high-purity argon, conduct vacuum arc melting, and repeat the melting at least 5 times to obtain ingots; where x can be 0.1, 0.2, 0.3, 0.4 or 0.5, or Other values in 0.1-0.5;

Roll the ingot to a thickness greater than the thickness set by the "transition layer material" during welding to obtain a rolled sheet;

Use wire cutting to cut the rolled sheet into a thin disc with the same diameter as the base metal;

Grinding and polishing the sheet with SiC sandpaper, cleaning with alcohol under the action of ultrasonic waves, and drying in a drying oven to finally obtain a high-entropy alloy "transition layer material" with a smooth surface. The final thickness of the high-entropy alloy "transition layer material" is 100-2000μm;

(2) Base material preparation: Cut the tungsten-cobalt hard alloy and 42CrMo round rods with the same diameter into the required length by wire cutting to obtain the tungsten-cobalt hard alloy round rods to be welded and the 42CrMo steel round rods to be welded. The surfaces of the tungsten-cobalt hard alloy round rods to be welded and the 42CrMo steel round rods to be welded are polished smooth to remove the oxide layer, etc., and the surfaces to be welded are finely polished Grinding, followed by polishing, and ultrasonic cleaning and drying of the tungsten-cobalt cemented carbide round rods to be welded and the 42CrMo steel round rods to be welded;

(3) Assembly: Tungsten-cobalt hard alloy, 42CrMo steel and (CoCrFeNi) _1-x Cu _x high-entropy alloy "transition layer material", from top to bottom according to graphite punch - graphite gasket - 42CrMo steel to be welded Round rod-(CoCrFeNi) _1-x Cu _x high-entropy alloy "transition layer material"-to-be-welded tungsten-cobalt hard alloy round rod-graphite gasket-graphite punch is assembled into the graphite mold in sequence, after assembling it The completed mold is put into the spark plasma sintering system;

(4) Discharge plasma SPS diffusion connection: put the graphite mold with the parts to be welded into the discharge plasma sintering system, adjust the infrared thermometer lens to the temperature measurement hole of the mold, adjust the diffusion connection pressure to 5-40Mpa, turn on the vacuum pump and inflate Pump to make the vacuum in the furnace ≤1×10 ^-3 Mpa, then pass the current to raise the temperature (heating rate 10-150°C/min) to the diffusion welding temperature (650-1000°C), then keep it warm for 5-30min, and perform SPS diffusion welding. Get a welded joint.

Specifically, the diffusion connection pressure can be 5Mpa, 8Mpa, 10Mpa, 15Mpa, 20Mpa, 25Mpa, 30Mpa, 35Mpa or 40Mpa, or other pressure values within this range;

The heating rate can be 10°C/min, 20°C/min, 30°C/min, 40°C/min, 50°C/min, 60°C/min, 70°C/min, 80°C/min, 90°C/min, 100°C °C/min, 110°C/min, 120°C/min, 130°C/min, 140°C/min or 150°C/min, or other values within this range;

Diffusion welding temperature can be 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, or other temperature values within this range;

The holding time can be 5min, 10min, 15min, 20min, 25min or 30min, or other time values within this range.

It should be noted that in the present invention, the shape of the base material and the high-entropy alloy "transition layer material" can also be square or other shapes in addition to being circular.

The method for connecting entropic ceramics and metals provided by the present invention will be described in detail below through specific examples.

Example 1

A method for connecting tungsten-cobalt hard alloys and 42CrMo steels using high-entropy alloys, comprising the steps of:

(1) Preparation of high-entropy alloy "transition layer material"

(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy Weigh Co, Cr, Fe, Ni and Cu raw materials in molar ratio, and then put them into the crucible of the vacuum melting furnace in order of melting point from low to high, in high-purity argon Under gas protection, vacuum arc melting is carried out, and the melting is repeated at least 5 times to obtain ingots;

Rolling the cast ingot to a thickness of 1000 μm to obtain a rolled sheet;

的薄圆片；Cutting of rolled sheets by wire cutting

of thin discs;

Grinding and polishing the thin wafer with SiC sandpaper, cleaning alcohol under the action of ultrasonic waves, and drying in a drying oven, and finally obtained a high-entropy alloy "transition layer material" with a smooth surface. The final thickness of the high-entropy alloy "transition layer material" is 700- 800μm;

(2), parent material preparation

的YG10X硬质合金和42CrMo圆棒切割成14.5mm长度，得到待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒，将待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒各表面打磨光滑，去除氧化层等，对待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒的待焊接面进行精细的打磨，随后进行抛光，再将待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒进行超声波清洗、干燥处理；cut the diameter

The YG10X hard alloy and 42CrMo round bars are cut into 14.5mm lengths to obtain the YG10X hard alloy round bars to be welded and the 42CrMo steel round bars to be welded. Grinding smooth, removing the oxide layer, etc., finely grinding the surface to be welded of the YG10X hard alloy round bar to be welded and the 42CrMo steel round bar to be welded, and then polishing, and then the YG10X hard alloy round bar to be welded and the 42CrMo steel round bar to be welded Steel round rods are ultrasonically cleaned and dried;

(3), assembly

The tungsten-cobalt hard alloy, 42CrMo steel and (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material", from top to bottom in accordance with graphite punch - graphite gasket - 42CrMo steel round rod to be welded - (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" - YG10X hard alloy round rod to be welded - graphite gasket - graphite punch is assembled into the graphite mold in sequence, and the assembled mold is put into the spark plasma sintering system;

(4), discharge plasma diffusion connection

Put the graphite mold with the parts to be welded into the discharge plasma sintering system, adjust the infrared thermometer lens to the temperature measurement hole of the mold, adjust the diffusion connection pressure to 10Mpa, turn on the vacuum pump and air pump to make the vacuum degree in the furnace ≤1×10 ^{- 3} Mpa, then pass the current to raise the temperature to 900°C at a rate of 100°C/min, then keep it warm for 15min, perform SPS diffusion welding, and then cool down with the furnace to obtain a welded joint.

For the final welded piece, a dog-bone tensile sample (sampled perpendicular to the welded surface) was taken from the middle of the welded piece by wire cutting, and the room temperature tensile performance was tested on a universal testing machine.

Please refer to Figure 1 to Figure 5 in combination, where Figure 1 is the YG10X cemented carbide obtained in Example 1 using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding it at 900°C for 15 minutes /(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" / 42CrMo steel joint structure morphology photo; Figure 2 is the use of (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" in Example 1 for SPS Diffusion welding, holding at 900°C for 15 minutes to obtain the microstructure photo of the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material"joint; Figure 3 is the (CoCrFeNi) _0.5 Cu used in Example 1 _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding, holding at 900 ° C for 15 minutes to obtain the (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material"/42CrMo steel joint structure morphology photos; Figure 4 is In Example 1, (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy was used as the "transition layer material" for SPS diffusion welding, and the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer" obtained at 900 ° C for 15 minutes Material" interface EDS line scan results; Figure 5 is the (CoCrFeNi) obtained in Example 1 using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as the "transition layer material" for SPS diffusion welding and holding at 900 ° C for 15 minutes Interface EDS line scan results of _0.5 Cu _0.5 high-entropy alloy "transition layer material"/42CrMo steel joint. It can be seen from the figure that the joints are well bonded and there are no obvious cracks. From the point analysis, it can be seen that the element diffusion at the interface in Figure 3 is relatively active, and there are copper-rich phases on the "transition layer material" side, Copper-poor phase, chromium-rich phase. At the interface in Figure 2, there is a similar phenomenon on the "transition layer material" side. Although the combination is also good, the interface is the weakest place in the tensile test, and the final fracture occurs there.

Example 2

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is only that: (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer Material" was replaced with (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material", other conditions were the same as in Example 1, finally obtained with (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as "transition layer material", using discharge plasma diffusion Welding realizes the connection of YG10X cemented carbide and 42CrMo steel.

The weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Please refer to Figure 6, Figure 7 and Figure 8 in combination, where Figure 6 is the YG10X obtained by using (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 2 and holding it for 15 minutes at 900°C Microstructure photo of _{cemented carbide/(CoCrFeNi) 0.6 Cu 0.4} high-entropy alloy "transition layer material"/42CrMo steel joint _; "Carry out SPS diffusion welding, and hold at 900 ° C for 15 minutes to obtain the microstructure and morphology of the YG10X cemented carbide/(CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material"joint; Figure 8 is the (CoCrFeNi) used in Example 2 ) _0.6 Cu _0.4 high-entropy alloy as the "transition layer material" for SPS diffusion welding, holding at 900 ° C for 15 minutes to obtain the microstructure and morphology of (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material"/42CrMo steel joint. It can also be seen from the figure that the overall joint bonding is better, but compared with Example 1, whether it is a YG10X cemented carbide/(CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material" joint or (CoCrFeNi) _0.6 Cu _{The 0.4} high-entropy alloy "transition layer material"/42CrMo joint has more defects.

Example 3

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is only that: (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer Material" was replaced with (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy "transition layer material", other conditions were the same as in Example 1, finally obtained with (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as "transition layer material", using discharge plasma diffusion Welding realizes the connection of YG10X cemented carbide and 42CrMo steel.

The weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Please refer to Figure 9 to Figure 11 in combination, where Figure 9 is the YG10X cemented carbide obtained by using (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 3 and holding it at 900°C for 15 minutes /(CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy “transition layer material”/42CrMo steel joint microstructure and morphology photo; Figure 10 is the SPS using (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as the “transition layer material” in Example 3 Diffusion welding, holding at 900°C for 15 minutes to obtain the microstructure photo of the YG10X cemented carbide/(CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy "transition layer material"joint; Figure 11 is the (CoCrFeNi) _0.7 Cu used in Example 3 SPS diffusion welding of _0.3 high-entropy alloy as the "transition layer material", and holding at 900°C for 15 minutes to obtain the microstructure and morphology of (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy "transition layer material"/42CrMo steel joint. It can be seen from the figure that it is similar to that of Example 2, although the overall connection of the joint is better, but there are more defects than that of Example 1.

Example 4

A method of connecting tungsten-cobalt-based cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is only that: (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material "Switch to (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material", other conditions are the same as in Example 1, finally obtain (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as "transition layer material", adopt spark plasma diffusion welding Realize the connection between YG10X cemented carbide and 42CrMo steel.

The weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Please refer to Figure 12-Figure 14 in combination, where Figure 12 is the YG10X cemented carbide obtained by using (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 4 and holding it at 900°C for 15 minutes /(CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material"/42CrMo steel joint microstructure and morphology photos; Figure 13 is the use of (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as the "transition layer material" in Example 4 for SPS Diffusion welding, holding at 900°C for 15 minutes to obtain the microstructure photo of the YG10X cemented carbide/(CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material"joint; Figure 14 is the (CoCrFeNi) _0.8 Cu used in Example 4 Microstructure photos of (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material"/42CrMo steel joint obtained by SPS diffusion welding as "transition layer material" at 900 _° C for 15 minutes. It can be seen from the figure that the structure and morphology of the (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material"/42CrMo joint is similar to the previous examples, but there are more defects than Example 1. In the YG10X hard It can be seen from the microstructure and morphology of the joint of high-entropy alloy/(CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material" that the (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material" near YG10X appears in the embodiment No enrichment phase observed in 2-3.

Example 5

A method of connecting tungsten-cobalt-based cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is only that: (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material "Switch to (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy "transition layer material", other conditions are the same as in Example 1, finally obtain (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as "transition layer material", adopt spark plasma diffusion welding Realize the connection between YG10X cemented carbide and 42CrMo steel.

The weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Please refer to Figure 15-Figure 17 in combination, where Figure 15 is the YG10X cemented carbide obtained by using (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as the "transition layer material" for SPS diffusion welding in Example 5 and holding it at 900°C for 15 minutes /(CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy “transition layer material”/42CrMo steel joint microstructure and morphology photos; Figure 16 is the SPS using (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy as the “transition layer material” in Example 5 Diffusion welding, holding at 900°C for 15 minutes to obtain the microstructure photo of the YG10X cemented carbide/(CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy "transition layer material"joint; Figure 17 is the (CoCrFeNi) _0.9 Cu used in Example 5 Microstructure photos of (CoCrFeNi) _0.9 Cu _0.1 high-entropy alloy "transition layer material"/42CrMo steel joint obtained by SPS diffusion welding as "transition layer material" at 900 _° C for 15 minutes. It can be seen from the figure that the structure and morphology of the (CoCrFeNi) _0.9 Cu _0.2 high-entropy alloy "transition layer material"/42CrMo joint is similar to that of the previous examples, but it also has more defects than Example 1, but it is more In Example 4, in the microstructure of the joint of YG10X cemented carbide/(CoCrFeNi) _0.9 Cu _0.2 high-entropy alloy "transition layer material", it can be seen that the (CoCrFeNi) _0.9 Cu _0.2 high-entropy alloy "transition" near YG10X There were more enriched phases than in Example 4 in "Layer Material".

Example 6

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the only difference is that the diffusion welding temperature is adjusted from 900°C to 950°C, other conditions and The same as in Example 1, finally obtained (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy as "transition layer material", using spark plasma diffusion welding to realize the connection of YG10X hard alloy and 42CrMo steel. The weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Example 7

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is that the diffusion welding temperature is adjusted from 900°C to 950°C, and (CoCrFeNi ) _0.5 Cu _0.5 high-entropy alloy "transition layer material" is replaced by (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material", and other conditions are the same as in Example 1, finally obtained with (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy as "Transition layer material", using spark plasma diffusion welding to realize the connection of YG10X cemented carbide and 42CrMo steel. And the weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Example 8

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is that the diffusion welding temperature is adjusted from 900°C to 950°C, and (CoCrFeNi ) _0.5 Cu _0.5 high-entropy alloy "transition layer material" is replaced by (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy "transition layer material", and other conditions are the same as in Example 1, finally obtained with (CoCrFeNi) _0.7 Cu _0.3 high-entropy alloy as "Transition layer material", using spark plasma diffusion welding to realize the connection of YG10X cemented carbide and 42CrMo steel. And the weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Example 9

A method of connecting tungsten-cobalt cemented carbide and 42CrMo steel using a high-entropy alloy in this embodiment, the experimental steps are repeated in Example 1, the difference is that the diffusion welding temperature is adjusted from 900°C to 950°C, and (CoCrFeNi ) _0.5 Cu _0.5 high-entropy alloy "transition layer material" is replaced by (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy "transition layer material", and other conditions are the same as in Example 1, finally obtained with (CoCrFeNi) _0.8 Cu _0.2 high-entropy alloy as "Transition layer material", using spark plasma diffusion welding to realize the connection of YG10X cemented carbide and 42CrMo steel. And the weldment that finally obtains, also is to get the dog-bone-shaped tensile sample (sampling perpendicular to the welding surface) from the middle of the weldment with wire cutting, and generally carry out the test of room temperature tensile performance on a universal testing machine with embodiment 1.

Comparative example 1

A connection method between tungsten-cobalt hard alloy and 42CrMo steel adopts pure copper as the transition layer material, and the process comprises the following steps:

(1) Preparation of pure copper "transition layer material"

紫铜薄片，其厚度为900μm(纯度≥99.95％)，随后将薄圆片用SiC砂纸打磨、抛光、超声波作用下酒精清洗、干燥箱干燥处理，最终得到表面光滑的纯铜“过渡层材料”，纯铜“过渡层材料”的最终厚度为700-800μm；diameter

Copper flakes, the thickness of which is 900 μm (purity ≥ 99.95%), and then the thin discs are ground and polished with SiC sandpaper, cleaned with alcohol under the action of ultrasonic waves, and dried in a drying oven to finally obtain a pure copper "transition layer material" with a smooth surface. The final thickness of the pure copper "transition layer material" is 700-800 μm;

(2) Base material preparation

的YG10X硬质合金和42CrMo圆棒切割成14.5mm长度，得到待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒，将待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒各表面打磨光滑，去除氧化层等，对待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒的待焊接进行精细的打磨，随后进行抛光，再将待焊YG10X硬质合金圆棒和待焊42CrMo钢圆棒进行超声波清洗、干燥处理；cut the diameter

The YG10X hard alloy and 42CrMo round bars are cut into 14.5mm lengths to obtain the YG10X hard alloy round bars to be welded and the 42CrMo steel round bars to be welded. Grinding smooth, removing the oxide layer, etc., finely grinding the YG10X hard alloy round bar to be welded and the 42CrMo steel round bar to be welded, and then polishing, and then the YG10X hard alloy round bar to be welded and the 42CrMo steel round bar to be welded The round bar is ultrasonically cleaned and dried;

(3) Assembly

Tungsten-cobalt hard alloy, 42CrMo steel and pure copper "transition layer material", from top to bottom according to graphite punch - graphite gasket - 42CrMo steel round rod to be welded - pure copper "transition layer material" - YG10X to be welded Carbide round rod-graphite gasket-graphite punch is assembled into the graphite mold in sequence, and the assembled mold is put into the spark plasma sintering system;

(4) Discharge plasma diffusion connection

Put the graphite mold with the parts to be welded into the discharge plasma sintering system, adjust the infrared thermometer lens to the temperature measurement hole of the mold, adjust the diffusion connection pressure to 10Mpa, turn on the vacuum pump and air pump to make the vacuum degree in the furnace ≤1×10 ^{- 3} Mpa, then pass the current to raise the temperature to 900°C at a rate of 100°C/min, then keep it warm for 15min, perform SPS diffusion welding, and then cool down with the furnace to obtain a welded joint.

For the final welded part, a dog-bone tensile sample was taken from the middle of the welded part by wire cutting, and the tensile properties at room temperature were tested. The final fracture position in the test was pure copper "transition layer material", not pure copper " Transition layer material" and the junction of YG10X cemented carbide and 42CrMo steel.

Please refer to Figure 18-Figure 20 in combination, where Figure 18 is the YG10X cemented carbide/pure copper "transition layer material" obtained by using pure copper as the "transition layer material" for SPS diffusion welding in Comparative Example 1 and holding it at 900°C for 15 minutes "/42CrMo steel joint structure morphology photo; Figure 19 is the YG10X cemented carbide/pure copper transition layer obtained by SPS diffusion welding using pure copper as the "transition layer material" in Comparative Example 1 and holding it at 900°C for 15 minutes Figure 20 is the pure copper "transition layer material"/42CrMo steel joint obtained by SPS diffusion welding at 900°C for 15 minutes in comparative example 1 Organizational photographs. It can be seen from the figure that the joints are in good condition.

With the diffusion welded joint that obtains in embodiment 1-9, comparative example 1, get the dog bone shape tensile sample (perpendicular to welding surface sampling) in the middle of welding sample, place on the universal testing machine and detect its tensile strength, its result As shown in Table 1.

Table 1: The maximum tensile strength of the tensile samples of each embodiment and comparative examples

From the tensile strength results of the joints in Table 1, it can be seen that under the same welding conditions, when pure copper is used as the "transition layer material", the weakest part of the joint is the pure copper "transition layer material", and the final resistance of the joint is Tensile strength is that of pure copper "transition material". Adopt (CoCrFeNi) _1-x Cu _x high-entropy alloy as " transition layer material ", when the value of x is 0.3-0.5, the tensile strength of joint exceeds adopting pure copper as " transition layer material " in embodiment 1-3 "The tensile strength. Example 1, which has the highest tensile strength in Examples 1-5, explains that the possible reason for its strength increase is that when using (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material", as shown in Figure 3, in ( CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" / 42CrMo joint microstructure at point E, the content of the main elements are: Fe (48.44%), Co (19.60%), Cr (7.69%) ), Ni(15.35%), Cu(8.92%), according to the calculation formula of mixing enthalpy:

为二元合金体系中基于Medema模型计算得到的第i种和j种组元之间的理想混合焓。其中Fe-Co的混合焓为-1kJ/mol，Fe-Cr的混合焓为-1kJ/mol，Fe-Ni的混合焓为-2kJ/mol，Fe-Cu的混合焓为13kJ/mol，Co-Cr的混合焓为-4kJ/mol，Co-Ni的混合焓为0kJ/mol，Co-Cu的混合焓为6kJ/mol，Cr-Ni的混合焓为-7kJ/mol，Cr-Cu的混合焓为12kJ/mol，Ni-Cu的混合焓为4kJ/mol经过计算可以得到ΔH_mix≈1.52kj/mol。in

is the ideal mixing enthalpy between the i-th and j-th components calculated based on the Medema model in the binary alloy system. Among them, the mixing enthalpy of Fe-Co is -1kJ/mol, the mixing enthalpy of Fe-Cr is -1kJ/mol, the mixing enthalpy of Fe-Ni is -2kJ/mol, the mixing enthalpy of Fe-Cu is 13kJ/mol, Co- The mixing enthalpy of Cr is -4kJ/mol, the mixing enthalpy of Co-Ni is 0kJ/mol, the mixing enthalpy of Co-Cu is 6kJ/mol, the mixing enthalpy of Cr-Ni is -7kJ/mol, the mixing enthalpy of Cr-Cu is 12kJ/mol, and the mixing enthalpy of Ni-Cu is 4kJ/mol. After calculation, ΔH _mix ≈1.52kj/mol.

Then calculate the atomic size difference δ, which can be calculated by the following formula:

表示平均原子半径，计算后可得

r _i represents the atomic radius of the i-th component in the high-entropy alloy,

Indicates the average atomic radius, which can be obtained after calculation

The atomic size difference δ can be calculated by the following formula:

When -2.68δ-2.54<ΔH _mix <-1.28δ+5.44 and δ<4.60, the microstructure of the alloy is composed of solid solution. The above calculation results conform to the above inequality and tend to form a solid solution. Similarly, the calculated ΔH _mix and δ of Fe (70.22%), Co (10.65%), Cr (5.57%), Ni (8.87%), and Cu (4.69%) at point F also conform to the above inequality. Solution strengthening increases the strength of the interface.

At the same time, from the EDS line scan results of the joint interface in Figure 5, it can also be seen that the diffusion behavior is relatively sufficient, and the number of defects is less, and the interface strength obtained by solidification is higher than that of YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high entropy The interface formed by the alloy "transition layer material" makes the final fracture of the tensile test appear near the interface formed by the YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material".

According to the EDS line scan results of the joint interface in Figure 4, it can be found that the diffusion distance of W in the "transition layer material" is relatively low, which may be due to the use of (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material", due to The hysteretic diffusion effect makes the diffusion distance of W in the "transition layer material" relatively low, while the main diffusion behavior found at the interface is that the (CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" diffuses to the YG10X cemented carbide side, which can It is found that the diffusion is more significant, and because the cobalt-based cemented carbide is used, the mixing enthalpy of Co-Fe is -1kJ/mol, the mixing enthalpy of Co-Cr is -4kJ/mol, and the mixing enthalpy of Co-Ni is 0kJ /mol, the mixing enthalpy of Co-Cu is 6kJ/mol, and the mixing enthalpy of Co-Ni is 0kJ/mol, which means that it is easier for Co to form a solid solution with Ni, which promotes the transition of Ni to YG10X The side diffusion of cemented carbide makes the diffusion more sufficient, and the bonding of the interface is also better, so that the maximum tensile strength of the interface formed by YG10X cemented carbide/(CoCrFeNi) _0.5 Cu _0.5 high-entropy alloy "transition layer material" Reach 508Mpa.

And in embodiment 6-9, raising temperature makes maximum tensile strength change, and reason is:

When the value of x increases, according to the mixing law, the theoretical melting points of the five "transition layer materials" are (CoCrFeNi) _0.9 Cu _0.1 ＞(CoCrFeNi) _0.8 Cu _0.2 ＞(CoCrFeNi) _0.7 Cu _0.3 ＞(CoCrFeNi) _0.6 Cu _0.4 ＞(CoCrFeNi) _0.5 Cu _0.5 , 900 degrees Celsius For the use of low melting point (CoCrFeNi) _0.5 Cu _0.5 "transition layer material", this welding condition has the energy required to produce more interfacial interdiffusion and reaction, while other The high-entropy alloy "transition layer material" requires a higher welding temperature or welding time, so compared with other "transition layer materials" with a higher theoretical melting point, there is only a very small amount of defects, while using (CoCrFeNi) _0.5 Cu _0.5 to improve the overall tensile strength of the joint, which is stronger than the overall tensile strength of the joint obtained by using the traditional pure copper "transition layer material". The joint interface and tensile strength of other high-entropy alloy "transition layer materials" may be improved and increased after increasing parameters such as welding temperature and diffusion time. Embodiments 6-9 correspond to Embodiments 1-4 in turn. They use the same high-entropy alloy "transition layer material", only the welding temperature is increased to 950 ° C, and other welding conditions are the same. Embodiment 7 and Embodiment 9 are compared The tensile strength of Example 2 and Example 4 is improved. When the welding temperature is increased to 950°C, the maximum tensile strength appears in Example 7 using (CoCrFeNi) _0.6 Cu _0.4 high-entropy alloy "transition layer material".

The invention adopts the method of connecting the tungsten-cobalt hard alloy and the 42CrMo steel with the high-entropy alloy, which helps to solve the problems of difficult welding and wetting of the tungsten-cobalt hard alloy and the 42CrMo steel and large residual stress caused by large difference in linear expansion coefficient. By introducing (CoCrFeNi) _1-x Cu _x high-entropy alloy as a "transition layer material", the tungsten-cobalt-based cemented carbide and 42CrMo steel were diffusion-bonded at a higher temperature (≥650°C). In this temperature range, the two Those with good wettability and interdiffusion between elements, using (CoCrFeNi) _1-x Cu _x high-entropy alloy "transition layer material" is difficult to form intermetallic compounds at the interface. With the help of the high-entropy effect, a uniformly distributed interface layer is formed, and the connection between the tungsten-cobalt cemented carbide and the 42CrMo steel, which has large differences in physical properties such as online expansion coefficient, melting point, and specific heat capacity, is realized. Reduce the local residual stress, inhibit the formation and expansion of cracks, and improve the joint strength. Finally _, the tensile strength of the tensile specimen of the weldment is greater than the tensile strength of the pure copper "transition layer material" _. Sintering (SPS) diffusion welding enables high-strength connections between tungsten-cobalt cemented carbide and 42CrMo steel.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and modifications to these embodiments without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (4)

1. A method for connecting tungsten-cobalt hard alloy and 42CrMo steel by adopting high-entropy alloy is characterized by comprising the following steps of (CoCrFeNi) _1-x Cu _x The high-entropy alloy is used as a transition layer material, and the tungsten-cobalt hard alloy and 42CrMo steel are subjected to solid-phase diffusion welding by an SPS technology, so that the connection of the tungsten-cobalt hard alloy and the 42CrMo steel is completed; wherein x=0.4-0.5;

the connection method comprises the following steps:

step S1, preparing a base material: cutting the tungsten-cobalt hard alloy and 42CrMo steel into a shape to be welded, and carrying out pretreatment;

step S2, assembling: cemented tungsten-cobalt alloy, 42CrMo steel and (CoCrFeNi) _1-x Cu _x The high entropy alloy material is assembled into a graphite mold, and (CoCrFeNi) _1-x Cu _x The high-entropy alloy material is positioned between the tungsten-cobalt hard alloy and the 42CrMo steel;

step S3, discharge plasma SPS diffusion welding connection: placing a graphite mold with a piece to be welded into a spark plasma sintering system, heating to a diffusion welding temperature under a vacuum condition, and then preserving heat to perform SPS diffusion welding; wherein the diffusion temperature is 800-950 ℃, and the diffusion welding time is 5-30min.

2. The method of joining a cemented tungsten cobalt-based alloy and 42CrMo steel using a high entropy alloy according to claim 1, wherein (CoCrFeNi) _1-x Cu _x The high-entropy alloy material is obtained by proportioning all alloy elements according to atomic ratio and then adopting vacuum arc smelting.

3. The method for joining tungsten cobalt-based cemented carbide and 42CrMo steel using high entropy alloy according to claim 1, wherein in step S2, (CoCrFeNi _1-x Cu _x The thickness of the high-entropy alloy material is 100-2000 mu m.

4. The method for connecting tungsten-cobalt-based cemented carbide and 42CrMo steel by high-entropy alloy according to claim 1, wherein in step S3, the heating rate is 10-150 ℃/min, the diffusion pressure is 5-40MPa, and the vacuum degree is less than or equal to 1×10 ^-3 Mpa。

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